Quantitative Functional Assessment of Ischemic Patients by Cardiopulmonary Exercise and Recovery Indices

Abstract

Exercise stress testing is commonly used for assessing the presence and severity of coronary ischemia including heart rate (HR) and blood pressure (BP) responses as well as exertional symptoms estimation (Vivekananthan et al., 2000). Cardiopulmonary exercise test (CPET) indices, obtained by direct measurement of exercise respiratory gas exchange, may provide additional important clinical information for further and more quantitative evaluation of the ischemic response. Among these indices are the ventilatory anaerobic threshold (VAT), oxygen consumption (VO2) and the oxygen pulse (O2-P) measured during exercise. These indices mainly reflect cardiac problems (Milani et al., 1995, 2006). However, recovery cardiopulmonary indices have been found to be an important tool for assessing the overall exercise capacity in patients with chronic heart failure (CHF). These indices differ significantly from healthy subjects. The kinetics of post exercise VO2 has been demonstrated to be delayed in relation to the severity of the disease and to be closely related to exercise capacity (Koike et al., 1998). Patients with severe CHF or dilated cardiomyopathy, demonstrated a prolonged recovery period to the baseline levels of VO2 (Pavia et al., 1999; De Groot et al., 1999). Similar results were found in patients with mitral stenosis (Lim et al., 1998). This chapter is based on our five studies, and concerns a quantitative functional assessment of ischemic response in patients with documented coronary artery disease (CAD). The ischemic response was tested using various classic and novel cardiopulmonary indices. The first study demonstrates four O2-P curve variables, achieved during exercise, which correlate well with different degrees of ischemic response. In the second study, the functional results following percutaneous transluminal coronary angioplasty (PTCA) were assessed in chronic CAD patients. In the third study there is a similar assessment of the effect of controlled exercise training in chronic CAD patients. In the fourth study the means by which ischemia can be improved, as a result of regular exercise training is explained. The most recent study deals with recovery indices of VO2 kinetics and their contribution to quantitatively assessing varying degrees of CAD.